Valve clearance gauges



Feb. 12, 1957 n. H. CAMPBELL VALVE CLEARANCE GAUGES Filed Feb. 20, 1955 IN VEN TOR. DEWEY H. CAMPBEU E BY Z ATTORNEY United States Patent z,7so,s71

VALVE CLEARANCE GAUGES Dewey H. Campbell, Newport, 0reg., assignor to P. & G. Manufacturing (10., Portland, Greg, a corporation of Oregon Application February 20, 1953, Serial No. 337,952

Claims. (Cl. 33-172) This invention relates to valve clearance gauges and has particular reference to a gauge for setting the clearance of overhead valves on an internal combustion engine.

In an overhead valve type of engine, the valve stems project upwardly through the cylinder head and are engaged by the ends of rocker arms which are actuated by tappets reciprocated by the engine cam shaft. The valves are urged upwardly toward closed position by individual coil springs on the valve stems exterior to the cylinder head. The upper end of each valve spring bears against an abutment washer secured to the valve stem a short distance beneath the upper end of the stem. In order to insure proper seating of the valves in closed position, it is necessary to allow a slight gap or clearance between the end of the valve stem and the rocker arm when the valves are closed. Excessive clearance, however, must be avoided because it would result in noisy operation and undue wear in the valve mechanism.

Adjustment means are ordinarily provided between the rocker aims and the tappets to maintain the proper clearance between the rocker arms and valve stems, and it is customary for manufacturers of overhead valve engines to include in the engine specifications the proper valve clearance for the guidance of mechanics. Such adjustment is necessary from time to time to compensate for ordinary wear, and is, of course, also necessary whenever the valves are ground or are replaced with new valves.

The usual type of gauge employed for measuring the clearance in making such adjustment is a leaf or feeler type comprising a thin strip of metal having a thickness equal to the desired clearance. The manipulations involved in using the gauge and varying the adjustment are of a trial and error nature which requires some skill and careful workmanship in order to achieve a fair degree of precision. Thus. it is a common experience to find that presumably identical valve adjustments made by ditferent mechanic will vary considerably, and there may even be a noticeable variation in the clearance adjustments of different valves on the same engine made by the same mechanic. All such departures from the optimum clearance value detract from the most quiet and efficient performance of the engine, and may even be injurious to the engine.

It is, therefore, the general object of the present invention to provide an improved gauge for measuring the valve clearance on overhead valve engines, in order to simplify the operation of making valve adjustments and improve the accuracy of such adjustments.

A particular object of the invention is the provision of a clearance gauge that can be set directly over the valve stem to give a direct reading of the valve clearance.

Another Object is to provide a gauge which will not interfere with the making of the valve adjustment and which will give a continuous indication of the clearance while the adjustment is being made.

These and other incidental objects will be apparent in the drawings, specification and claims.

Referring to the drawings:

Figure 1 is a side view of my new and improved valve clearance gauge;

Figure 2 is a fragmentary side sectional view of the head of a motor, including the upper end of the valve stem and the rocker arm assembly, showing my gauge applied thereto, part of the gauge being shown in section;

Figure 3 is a front view of the gauge, taken on the line 3-3 of Figure 2; and

Figure 4 is a plan detailed fragmentary sectional view, taken on line 44 of Figure 3, the rocker arm indicated in broken line for convenience of illustration.

Referring more specifically to the drawings:

My new and improved clearance gauge consist of a tubular body 1 having a flared base 2, which is adapted to rest on the spring retaining washer 3 of the valve 4. A second tubular member 5 is slidably mounted within the body 1. The tubular member 5 is held in a raised position by the spring 6.

The upper end of the spring 6 is supported by the cross pin 7, which is fixedly secured within the upper end of the tubular body at 8. The lower end of the spring is hooked onto the cross pin 9, the said pin 9 being fixedly secured at 10 to the tubular member 5. Slots 11 are formed in the member 5, permitting the same to be raised and lowered relative to the cross pin 7.

The lower end of the body member 1 is notched out at 12 and the lower end of the member 5 is notched out at 13. Located on the lower end of the member 5 is a flange or foot 14. This foot is adapted to engage the underside 15 of the rocker arm 16 of the motor, as best illustrated in Figures 2, 3 and 4. The spring 6 pulls the said foot up against the underside 15 of the rocker arm and holds the body member 1 in an upright position firmly seated on washer 3 so that the body member does not have to be held in operative position by the operator.

An outwardly extending arm 17 is fixedly secured to the inner tubular member 5 at 18. A thumb screw 19 is threaded into this arm and has a knurled head 20 for adjusting the same up and down in relation to the said arm.

A standard dial type micrometer gauge 21 is adjustably secured to the main body 1 by the clamp 22, as best illustrated in Figure l. The plunger 23 of the gauge 21 engages the upper surface of the thumb screw 19 at 24. The gauge 21 is preferably of the multiplying direct reading type wherein the plunger 23 is connected to a revolving pointer through a. motion multiplying train (not shown). The arrangement is such that minute movements of foot 14 relative to base 2 are magnified and indicated directly on the dial oi the gauge in fractional units of distance measurement.

1 will now describe the operation of my new and improved clearan-ce gauge. The gauge assembly is brought in from the side of the valve stem so that the openings 12 and 13 straddle the end of the rocker arm 16 and the upper end of the valve stem 4. The body member 1 is centered over the said stem, the base 2 resting on the retaining washer 3.

When the gauge assembly is slipped over the side of the upper end of the stem, the thumb of the operator forces the inner tubular member 5 down against the spring 6, lowering the foot 14 sufliciently to pas under the end of the rocker arm 16. Then member 5 is released, allowing spring 6 to bring the foot up against the under surface 15 of the rocker arm. The foot 14 and base 2 being urged apart by spring 6 thereby form a spring clamp to secure the device in operative position on the valve stem.

The next operation is to raise the opposite end of the rocker arm 16 by a tool, as indicated by broken lines, so as to take up the clearance between the upper end of the valve stem and the lower surface of the rocker arm. The knurled head 20 is then adjusted so that the pointer of the gauge will register zero. The rocker arm is then released by the tool above described, at which time the spring 6 will raise the rocker arm away from the valve stem. This will cause the plunger 23 of the gauge to be forced upwardly by the thumb screw 19 on the arm 17 which is carried by the tubular member 5.

The amount the tubular member 5 is raised by the spring 6 before the adjusting screw assembly 25 of the rocker arm limits the upper travel of the rocker arm above the valve stem will be indicated on the gauge. that is necessary to do is to adjust the valve clearance screw 25 so as to lower or raise the tubular member 5 until the gauge indicates the desired clearance. When this is determined, the operator forces the tubular member 5 down with his thumb, which lowers the foot 14 so that the unit can be slid sideways and removed from the valve and rocker arm assembly.

Thus, the present gauge tends to eliminate human error and variation and gives a mechanical reading of uniform accuracy in all operations independently of the skill of the mechanic. The gauge holds itself in position while the clearance adjusting screw is being manipulated, leaving the operators hands free to accomplish that task. A simple and direct procedure is substituted for the conventional tedious trial and error technique.

What is claimed is:

l. A valve clearance gauge device for measuring the free travel between confronting surfaces of a relatively movable rocker arm and rod assembly of a valve engine, comprising a rod engaging member proportioned and arranged to removably engage the confronting surface of said rod, a rocker arm moving member proportioned and arranged to removably engage the confronting surface of the rocker arm, means interconnecting said members for relative displacement in the direction of displacement of said confronting surfaces and including resilient means adapted to move said members in the direction of separation of said confronting surfaces to the llimit of said free travel, the resilient means being of suflicient strength further to move the rocker arm to the limit of said free travel, and indicator means operatively interconnecting said members and operative upon relative movement of the rocker arm and rod to indicate the magnitude of said free travel.

2. The device of claim 1 wherein the indicator means includes adjustment means operable independently of said resilient means to adjust the indicator reading to an initial value.

3. A device for measuring the clearance between a valve actuating rocker arm and a valve stem of an overhead valve having a spring retaining washer, comprising a body member having an arcuate wall on one end thereof shaped to partially surround the end of the valve stem and seat on the spring retaining washer, said wall having an opening in one side to receive the end of the rocker arm overlying the valve stem, a movable member mounted on said body member and having a hook portion to engage under the end of the rocker arm, spring means connected between said body member and said movable member biasing said movable member in a di- Thcn all rection to move the rocker arm away from the valve stem, said wall of said body member and said hook portion of said movable member forming a spring clamp to secure means mounted on one of said members and having actuating means operable by the other member for measuring the clearance between the rocker arm and valve stem.

4. A device for measuring the clearance between a valve actuating rocker arm and the valve stem of an overhead valve having a spring retaining washer, comprising a tubular support which is open at one end to surround the end of a valve stem and seat on the valve spring retaining washer, said support having a longitudinal slot opening through said end to accommodate the end of the rocker arm overlying the valve stem, a member slidably mounted in said tubular support and having a hook portion on the end adjacent the open end of said support to engage under the end of the rocker arm, spring means carried by said support and biasing said member inwardly from said open end to move the rocker arm from the valve stem, a gauge fixedly mounted on said tubular support and having an actuating plunger extending toward said open end and aligned with said slot in said support, an arm on said member and extending through said slot in said support, and an abutment adjustably mounted on said arm and engaging said gauge actuating plunger to indicate on said gauge the clearance of the rocker arm relative to the valve stem.

5. A device for measuring the clearance between the valve actuating rocker arm and the valve stem of an overhead valve having a spring retaining washer, comprising a tubular support which is open at both ends with one of said ends forming a seat, said support having a longitudinal slot opening through said seat end and adapting said end for straddling the end of the rocker arm and surrounding the end of the valve stem to seat against the valve spring retaining washer, a tubular member slidable in said support, said member being open at the end corresponding to said seat end of the support and having a slot opening through said end to accommodate the end of the rocker arm, a lip on said member opposite said slot and extending inwardly of said member to engage under the end of the rocker arm, a pin fixed transversely within said support, said member having oppositely disposed 1ongitudinal slots to pass said pin, a pin fixed transversely within said tubular member, a spring anchored between said pins and biasing said member inwardly away from said seat end to move the rocker arm away from the valve stem, the other end of said tubular member extending beyond said support and adapted to be manually pressed to move said member in opposition to said spring to initially engage said lip under the rocker arm, a gauge fixedly mounted on said tubular support and having an actuating plunger extending toward said seat end and aligned with said slot in said support, an arm on said member and extending through said support slot for movement with said member relative to said plunger, and a screw abutting said plunger and threaded in said arm in alignment with said plunger for adjustment relative to said plunger.

References Cited in the file of this patent FOREIGN PATENTS 227,940 Great Britain Jan. 27, 1925 

